Valve lifter



1965 J. DORNBOS 3,200,801

' VALVE LIFTER Original Filed Nov. 2, 1960 IN VEN TOR.

BY c/Zz m ar/250s HTTOE/VEY United States Patent 3,2tltl,t-ltll VALVE LETER John Dornbos, Grand Rapids, Mich, assignor to General MotorsCorporation, Detroit, Mich, a corporation of Delaware Originalapplication Nov. 2, 1960, Ser. No. 66,371, new Patent No. 3,149,410,dated Sept. 22, 1964. Divided and this application Mar. 11, 1964, Ser.No. 351,016

The present patent application is a division of my copending UnitedStates application serial No. 66,871, which was filed on November 2,1960, and is now Patent No. 3,149,410, and is owned by the assignee ofthe instant patent application.

This invention relates to a composite valve lifter and similar articlesand to an improved method of making same.

It is well known that valve litters, both mechanical and hydraulic, areoperated under conditions which are corrosive to the metals used inmaking the lifters. The elfect of the corrosive conditions does notcreate an especially critical problem with regard to mechanical lifters.Hydraulic valve lifters, on the other hand, can be particularlydeleteriously affected by these corrosive conditions. Corrosion of theinner wall of the body of the hydraulic lifter, as well as the outermating wall of the plunger results in increasing the space therebetweento such an extent as to permit rapid leakdown of the lifter which, ofcourse, renders the li ter functionally inoperative.

The outer surface of the plunger and inner surface of the body are insliding contact with one another. Corrosion products accumulating onthese surfaces are wiped oil during operation of the lifter yielding afresh surface which can be corroded. As this process is continuousduring operation of the lifter, it is readily seen that an extremelylarge gap can be acquired between the mating surfaces of the body memberand the plunger due to corrosion.

Attempts to produce a more corrosion-resistant valve lifter by merelymaking the plunger out of stainless steel only reduces the corrosionproblem by one half. Corrosion of the inner surface of the body memberstill remains a problem. Forming the plunger and the body member out ofstainless steel would virtually eliminate the aforesaid corrosionproblem. Unfortunately, heretofore there was no commercially practicalmeans for securing the cast iron foot piece to the stainless steelmeat-- ber.

Due to the continuous succession of shocks and various dynamic stressesto which a valve litter is subjected, it is readily apparent that anexceptionally strong bonding of the cast iron end cap to the stainlesssteel tubular body member must be obtained. Moreover, for commercial useit is of extreme importance that this strong bond be consistently buteconomically obtained under the comparatively wide tolerances inherentlyinvolved with commercial production conditions.

Although various methods of bonding stainless steel to cast iron havebeen proposed, no such method alone, under commercial productionconditions, will consistently yield a valve lifter having the requiredreliability demanded for commercial applications. I have found that thecriticalities and inherent expenses involved in bonding stainless steelto cast iron can be materially reduced by employing my valve lifterstructure. My valve lifter construction obviates the usual probleminherently involved in securing the cast iron foot piece to a stainlesssteel body by forming a two-piece body for the valve lifter of aspecific construction.

Accordingly, a primary object of the invention is to provide an improvedvalve lifter construction and method of forming same.

Other objects, features and advantages of the invention will become moreapparent from the following description of a specific example thereofand from the drawing, in which:

FTGURE .1 shows a sectional view taken longitudinally through a valvelifter, such as can be formed in accordance with the present invention;and

FIGURE 2 shows an exploded elevational view in perspective of an end capand two-piece body member used to produce a valve lifter, such as shownin FlG- URE 1.

As previously indicated, the invention comprehends forming a two-piecebody for the valve lifter in which a major portion of the body is formedof a stainless steel tubular member while a minor portion of the body isformed of a low alloy steel tubular member. In assembly the low alloysteel portion of the body is interposed between the stainless steelportion and an alloy cast iron foot piece of the valve lifter.

Although interposing the low alloy steel between the alloy cast iron andthe stainless steel provides some advantages from a metallurgicalstandpoint, it has been found that a satisfactory valve litter cannot beformed unless the outer diameter of the stainless steel portion of thevalve lifter is brazed to the inner diameter of the low alloy steeltubular member. Moreover, an extremely tight fitting relationship mustexist between the mating surfaces of these two portions of the bodymember.

A more detailed description of the invention can be made clearer byreference to a specific example of the valve lifter constructioncontemplated by the invention. For this reason, attention is directed tothe drawing which shows a hydraulic lifter that is made in accordancewith the invention. The valve lifter generally comprises a two-piecetubular body it) having a stainless steel portion 12 and a low alloysteel portion 14 to which an alloy cast iron foot piece or end cap 16 issecured. The stainless steel part 12 and the low alloy steel part 14 arebrazed together as shown at 13. The alloy cast iron foot piece 16 isbrazed to the low alloy steel part 14 as shown at 15.

The end cap 16 is a generally cylindrical member, a portion 1% of whichis relieved, of a reduced diameter, for insertion in a close fittingrelationship with the inner circumference 20 of the low alloy steelportion 14 of the tubular body. The alloy cast iron end cap abuts theend surface 22 of the low alloy steel portion of the body when the endcap and the body It are assembled. The outer periphery 24 of thestainless steel portion 12 of the body is relieved, of a reduceddiameter 26 at one ed, for insertion within the low alloy steel portion14 of the body ltl. This reduced diameter portion 26 gives rise to ashoulder 28 which preferably abuts the end of the low alloy steel member14 opposite to end 22.

The outer periphery of the tube 12 is also relieved by an annular grooveSt The bore 32 of the tube 12 is relieved by an annular groove 34 whichconnects with the outer groove 30 by a side wall port 36. A stainlesssteel cup-shaped plunger 38 whose external periphery is relieved by anannular groove ll) is in close telescopic sliding fit in the bore 32 ofthe tube 12. The stainless steel plunger 38 is preferably carburized inany suitable manner to improve its Wear resistance. The groove 4t) inthe plunger 38 is made sufficiently wide to have continuouscommunication with the tube internal groove 34 during relative movementtherebetween, and is connected to a reservoir 42 within the plunger 38by a side wall port 44.

aacaeor Oil from the engine lubricating system flows into the plungerreservoir from a gallery in a cylindrical block (not shown) via the tubeouter groove 30, port 36, tube inner groove 34, plunger groove 40 andport 44. The tube innergroove 34 overlaps the upper edge of the plungergroove 40 and the latter overlaps the lower edge of the tube innergroove sufliciently so that in all relative positions of the plunger 38and tube 12 there is communication between the ports 36 and 44. Theplunger 38 is spaced from the tube 14 to provide a groove 46 which isopen at all times to the pressure chamber 48 between the plunger 38 andfoot piece 16.

Connecting the pressure chamber 48 with the reservoir 42 in the plunger38 is a passage 50 whose lower end is normally closed by a check valveshown in the form of a ball 52. Enclosing the ball is a generallycup-shaped retaining cage 54 whose open end is externally flanged andslotted as at 56 to abut the plunger and accommodate passage of oilbetween the passage 50 and the pressure chamber 48 when the ball 52 isdisplaced from its seated position shown. A small biasing spring 58between the ball 52 and the bottom of the cage 54 tends to maintain theball seated. The bottom end wall of the plunger is recessed to receivethe cage flange within a depending annular skirt portion 60. Theinternal periphery 62 of this skirt portion 60 has a tight frictionalfit with the lateral extremities of the slotted cage flange to retainthe cage 54 in assembly with the plunger 38 during its installation orremoval from the tube 12. Seated against the cage flange is one end of acoil compression spring 64 which reacts against the foot piece 16 inurging the plunger 38 outwardly of the tube 12.

. The alloy cast iron foot piece 16 includes a bottom diskshaped portion66 which abuts the bottom end face of the tube and is permanently bondedthereto in a manner described herein. Integral with the disk-shapedportion 66 is the diametrically smaller annular portion 18 having anouter diameter sufficient to make a tight press fit with the internalperiphery 20 of the tube 14-. This annular portion 18 also provides awell 68 in which the bottom end of the plunger return spring 64 issocketably seated, and the upper end of this annular portion provides ashoulder 70 engageable by the plunger skirt portion 60 to limit extremeinward movement of the plunger 38.

A push rod (not shown) is supported at its lower end on the plunger by apush rod seat member 72. The push rod seat member is formed with aflange portion 74 overlying the upper open end of the plunger 38 and hasits lower end 76 extending somewhat into the plunger to locate itlaterally thereof.

Satisfactory results are attainable when the relieved area 26 of thestainless steel tube 12 has a diameter at least the same as the innerdiameter of the low alloy steel tube 14. Best results under commercialproduction conditions are attainable when the diameter of the relievedarea 26 is up to 0.005 inch greater than the inner diameter of the lowalloy steel tube 14. The reduced diameter portion 18 of the end cap alsoshould have a greater diameter than the inner diameter of the tube 14.

The portion 18 of the end cap preferably has a diameter betweenapproximately 0.004 inch to 0.03 inch greater than the inner diameter ofthe tube 14.

In making a valve lifter, such as hereinbefore described, a stainlesssteel seamless tube is suitably relieved at one end to a diameter ofabout 0.0005 inch greater than the inner diameter of a low alloy steelseamless tube. The outer periphery of the tubes can be of any suitablediameter, as this surface of these tubes is subsequently machined to theproper dimensions.

The parts preferably are cleaned to remove dirt, grease, etc. in thenormal and accepted manner as by degreasing in trichloroethylene or thelike. The relieved area of the stainless steel tube is then press fittedinto the low alloy steel tube and a suitable copper brazing compoundapplied to the inner circumferential joint formed therebetween.

The assembly is heated in a hydrogen atmosphere for approximately 40minutes to effect the braze and then cooled under a protectiveatmosphere to room temperature.

The alloy cast iron foot piece is preferably joined to the two-piecebody by brazing in the following manner. The foot piece is cleaned toremove rust, dirt, grease, etc. by wheel-abrating and degreasing in thenormal and accepted manner. After degreasing, the part is pickled in asuitable acid solution, such as immersion for about two minutes in anaqueous solution containing about 10%, by weight, muriatic acid.

After pickling, the part is rinsed to remove the acid adhering theretoand placed in an aqueous solution containing about 2.5 ounces to 3ounces potassium cyanide per gallon of water. After immersion in thepotassium cyanide solution for about two minutes the end piece isremoved therefrom and directly placed into an aqueous bronze platingbath which is as follows:

Oz./gal. Free KCN 3.0

KCu(CN) 3.0 KOH A 0.4 K Sn(OI-I) 13.5

A layer of a bronze alloy containing about 30%, by weight, tin and about70%, by weight, copper, approximately 0.001 inch in thickness isdeposited. The layer is formed under a cathode current density ofapproximately 10 :amperes per square foot and a bath temperature ofabout F., using copper anodes.

The bronze plated foot piece is rinsed in water, dried and press fittedinto the open end of the low alloy steel portion of the previouslybrazed two-piece body. The three-piece assembly is heated to atemperature of ap proximately 1650 F. under a hydrogen atmosphere forabout 40 minutes to braze the foot piece to the body. It is then cooledin the hydrogen atmosphere to room temperature.

The brazed three-piece assembly is then ground and finish machined. Itis then carburized at a temperature of approximately 1650 F. for about 2/2 hours, oil quenched, and tempered at about 300 F. for one hour.

It is not only essential to the successful production of acorrosion-resistant valve lifter in accordance with my invention thatthe two-piece body be formed with a low alloy steel and stainless steel,it is imperative that the low alloy steel portion of the body beinterposed between the stainless steel portion and an alloy cast ironfoot piece. It is also essential that the inner circumference of the lowalloy steel portion be brazed to an outer circumference of the stainlesssteel member to attain consistent satisfactory results under commercialproduction conditions.

For purposes of this invention the term stainless steel is intended toencompass all those ferrous alloys (alloys having more than 50% iron)containing in excess of 10%, by weight, chromium. Especiallysatisfactory stainless steels for commercial applications are found inthe SAE 300 and SAE 400 series stainless steel. The term low alloysteel, as used herein, refers to various ferrous alloys in which thetotal alloy content, alloying ingredients other than iron, is less thanabout 8%, such as is normally understood by the term, and in which thecarbon content is less than about 0.8%, by W Especially satisfactory lowalloy steels for commercial applications are found in the SAE 1010 toSAE 1020 series steels. The term alloy cast iron, as used herein,comprehends those cast irons ferrous alloys having a carbon content ofabout 1.7% to 4.5%, by weight,) which contain about 2.8% to 3.3%, byweight, carbon along with appropriate amounts of silicon and significantam u of alloying ingredients in addition to carbon and silicon. Theadditional alloying ingredients frequently involve one or more from thegroup including nickel, chromium and molybdenum.

As specific examples, the following table lists the composition of asuitable alloy of each or" the above-mentioned types of ferrous alloys:

It is to be understood that although the invention has been described inconnection with certain specific examples thereof, no limitation isintended thereby except as defined in the appended claims.

I claim:

1. A valve lifter comprising a low alloy steel tubular member, astainless steel tubular member and a cast iron end cap, the stainlesssteel member and the end cap being brazed to an inner circumference ofthe loW alloy steel tubular member.

2. A hydraulic valve lifter comprising a two-piece tubular body formedof a W alloy steel tubular member and a stainless steel tubular member,the latter having an outer circumference brazed to an innercircumference of the former, an alloy cast iron end closureimperforately secured to the low alloy steel tubular member, and astainless steel plunger disposed Within said stainless steel tubularmember in working relationship therewith.

3. A valve lifter comprising a first tubular member, a second tubularmember and a Wear-resistant end closure for said first tubular member,said first tubular member being formed of a ferrous alloy having lessthan about 8%, by Weight, total alloy content and less than about 0.8%,by Weight, carbon, said second tubular member being formed of a ferrousalloy containing at least about 10%, by Weight, chromium, and said endclosure being formed of an alloy cast iron having about 2.8% to 3.3%, byWeight, carbon, an outer circumference of the second tubular member andsaid end closure being brazed to an inner circumference of the firsttubular member at cpposite ends thereof.

4. A hydraulic "alve lifter comprising a two-piece tubular body formedof a low alloy steel tubular member and a stainless steel tubularmember, the latter having an outer circumference brazed to an innercircumference of the former, and an alloy cast iron end closureimperforately secured to the low alloy steel tubular member.

5. A hydraulic valve lifter comprising a two-part tubular body, thefirst of said parts being formed of a ferrous alloy having less than 8%,by weight, total alloy content and less than about 0.8%, by Weight,carbon, the second of said parts being formed of a ferrous alloy havingat least about 10%, by Weight, chromium, the second part having an outercircumference brazed to an inner circumference of the first part at oneend thereof, an alloy cast iron end closure imperforaitely secured tothe other end of the first part, and a stainless steel plunger disposedWithin the second part in Working relationship therewith.

References (Cited by the Examiner UNITED STATES PATENTS 1,582,883 4/26Rich 123-90 1,747,490 2/30 Schneider et al 123-9O 1,973,855 9/34 Long123-90 2,759,249 8/ 56 Eberle 29-4-72.1 2,845,914 8/58 Coho 12390FOREIGN PATENTS 827,315 2/60 Great Britain.

FRED E. ENGELTHALER, Primary Examiner.

5. A HYDRAULIC VALVE LIFTER COMPRISING A TWO-PART TUBULAR BODY, THEFIRST OF SAID PARTS BEING FORMED OF A FERROUS ALLOY HAVING LESS THAN 8%,BY WEIGHT, TOTAL ALLOY CONTENT AND LESS THAN ABOUT 0.8%, BY WEIGHT, CARBON, THE SECOND OF SAID PARTS BEING FORMED OF A FERROUS ALLOY HAVING ATLEAST ABOUT 10%, BY WEIGHT, CHROMIUM, THE SECOND PART HAVING AN OUTERCIRCUMFERNCE BARZED TO AN INNER CIRCUMFERENCE OF THE FIRST PART AT ONEEND THEREOF, AN ALLOY CAST IRON END CLOSURE IMPERFORATELY SECURED TO THEOTHER END OF THE FIRST PART, AND A STAINLESS STEEL PLUNGER DISPOSEDWITHIN THE SECOND PART IN WORKING RELATIONSHIP THEREWITH.